(I know that No. 6 isn't really considered Shounen-Ai, but to me it is.)
I only buy what I can watch more than once, so with that in mind, here's the list:
A list of the funniest series I've watched, though they don't have to specifically be comedy series.
Series under 14-16 episodes.. for an anime-fix when there isn't the time // focus for lengthy shows!